1. Field of the Invention
This invention relates generally to a process for preparation of a component of a catalyst for polymerization of .alpha.-olefins, and more particularly to a process for preparation of a specific component of a catalyst mainly consisting of titanium trichloride used for homopolymerization or copolymerization of .alpha.-olefins.
2. Description of the Prior Art
Solid titanium trichloride and a solid composition of titanium trichloride and aluminum trichloride have been widely known in the art as a catalyst component for polymerization of .alpha.-olefins. The titanium-containing catalyst components are prepared, for example, by reducing titanium tetrachloride with metallic titanium or hydrogen, or reducing titanium tetrachloride with metallic aluminum or an organo aluminum compound. However, these components are not satisfactory in a polymerization activity per unit quantity of the catalyst component and a yield of stereoregular polymer to be produced when they are used for polymerization of .alpha.-olefins.
There have been proposed several processes for improving the titanium-containing catalyst component for the polymerization of .alpha.-olefins, such as, for example, the process for milling the solid titanium trichloride together with an electron donor such as ether or the like, the process for milling the titanium trichloride with an ester of organic acid or organic polysiloxane, and the process for milling the titanium trichloride with ether-titanium tetrachloride complex. In addition, there have been proposed chemical treatments of the catalyst component for increasing the activity and stereospecificity of the catalyst by cleansing the catalyst component with an organic solvent or the like during or after the preparation thereof.
Nevertheless, such an improvement is still insufficient to satisfy the requirements of manufacturers of .alpha.-olefins, because it is required that the catalyst component be manufactured at low cost as well as exhibiting an excellent polymerization activity per unit quantity thereof and increasing the yield of stereoregular polymer. In order to meet such requirements, it is highly desirable to develop techniques for preparing the catalyst component exhibiting excellent catalytic activity by a simplified process capable of accomplishing energy savings and eliminating cleansing with a large amount of organic solvent. In this connection, the chemical treatment of the catalyst component as described above necessarily requires cleansing with a large amount of the solvent, although it exhibits satisfactory polymerization activity and produces stereoregular polymer at high yields.
Further, the conventional high efficiency catalyst component is easily affected by a temperature and the like with the increase in performance. Thus, it is required to give full consideration to temperature by providing cooling or refrigeration facilities during the storage and transportation. This is a large burden on the user.